EASY
JEE Advanced
IMPORTANT
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Two objects that are moving along an x y -plane on a frictionless floor collide. Assume that they form a closed. isolated system. The following table gives some of the momentum components (in kilogram meters per second) before and after the collision. What are the missing values a, b?

  Before collision After collision
Object  pX pY pX pY
A -4 5 3 a
B b -2 4 2

 

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Important Questions on System of Particles and Centre of Mass

EASY
JEE Advanced
IMPORTANT

Figure shows a hollow cube of side ' a ' and volume ' V. There is a small chamber of volume V/4 in the cube as shown. The chamber is completely filled by m kg of water. Water leaks through a hole H and spreads in the whole cube. Then the work done by gravity in this process assuming that the complete water finally lies at the bottom of the cube is

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HARD
JEE Advanced
IMPORTANT

A block 'A' of mass m, hits horizontally the rear side of a spring (ideal) attached to a block B of mass m2 resting on a smooth horizontal surface. After hitting, ' A ' gets attached to the spring.

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Some statements are given at any moment of time:
i. If velocity of A is greater than B, then kinetic energy of the system will be decreasing.
ii. If velocity of A is greater than B, then kinetic energy of the system will be increasing.
¡ii. If velocity of A is greater than B, then momentum of the system will be decreasing. iv. If velocity of A is greater than B, then momentum of the system will be increasing.
Now select correct alternative:

EASY
JEE Advanced
IMPORTANT
A strip of wood of mass M and length l is placed on a smooth horizontal surface. An insect of mass m starts at one end of the strip and walks to the other end in time t, moving with a constant speed. The speed of the insect as seen from the ground is
 
MEDIUM
JEE Advanced
IMPORTANT

Two blocks of masses m and 4 m lie on a smooth horizontal surface connected with a spring in its natural length. Mass m is given velocity v0 through an impulse as shown in figure. Which of the following is not true about subsequent motion?

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HARD
JEE Advanced
IMPORTANT
A block A of mass M=2 kg is connected to another block B of mass 1 kg with a string and a spring of force constant k=600 N m-1 as shown in the figure. Initially the spring is compressed to 10 cm and the whole system is moving on a smooth surface with a velocity v=1 m s-1 . At any time thread is burnt, the velocity of block A , when B is having maximum velocity with respect to the ground, is


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EASY
JEE Advanced
IMPORTANT

Two identical blocks, having mass M each, are conjugated and placed on a smooth floor as shown in figure. A small block of mass m is released from position as shown. Velocity of block B is maximum

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MEDIUM
JEE Advanced
IMPORTANT

In figure, a hollow tube of mass M is free in horizontal direction. The system is released from rest. There is no friction present. The tube and blocks are taken as system.

i. Momentum of the system is conserved in x -direction.
ii. Speed of A w.r.t. M= Speed of B w.r.t. M

¡ii. Trajectory of centre of mass is X -constant. iv. Centre of mass has finite acceleration.
Evaluate the above statements and choose the correct option from the following:

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EASY
JEE Advanced
IMPORTANT
A trolley is moving horizontally with a velocity of v m/s w.r.t. earth. A man starts running in the direction of motion of trolley from one end of the trolley with a velocity 1.5v m/s w.r.t. the trolley. After reaching the opposite end, the man turns back and continues running with a velocity of 1.5 v m/s w.r.t. trolley in the backward direction. If the length of the trolley is L, then the displacement of the man with respect to earth, measured as a function of time, will attain a maximum value of